The invention relates to a blood centrifugation cell, particularly a cell in which blood can be processed on a continuous basis for the withdrawal of red corpuscles without interruption of inflow or rotation. It is well known that blood centrifugation to achieve separation of the red corpuscles from the other blood components, such as plasma, white corpuscles and platelets, is currently achieved in devices known as cells or bowls. These cells usually include a bell-shaped (truncated-cone shaped) outer container of a desired volume. A somewhat smaller but similarly shaped volume displacement body having a central passage is coaxially enclosed within the container to facilitate separation. The body can be described as a solid of revolution having a cylindrical inner wall and a truncated conical outer wall which are hermetically sealed at the upper and lower edges of the walls. The cell includes a stationary housing which is connected to and which encloses the upper end of the container. The connection includes an annular, rotatable bearing with suitable gaskets and seals. The housing has two generally coaxial conduits extending into the container and adapted for external connections to tubing for the inflow of blood and the outflow of blood components. The central inner conduit extends through the central passage in the body and extends down to the bottom of the container. The outer conduit at its lower end, is in communication with an annular passage formed between two facing discs positioned at the base of the stationary housing, that is, in the space portion at the top of the container. In these known cells, the outer container is gripped and rapidly rotated by a rotating mandrel. The whole blood is fed into the cell through the inner conduit and reaches the bottom of the outer container where it is subject to a centrifugal force; as a consequence thereof, the red corpuscles, which are heavier, collect and concentrate against the wall of the outer container, separated at a substantially vertical front from the lighter fractions, constituted by plasma, platelets, and white corpuscles, which remain inwards.
As the process continues, the inflow of whole blood causes the level of the components separated in the container to rise, and at a certain point, the light components begin to enter the passage between the two discs of the stationary housing, then travel along the outer conduit and are evacuated. The process continues until the concentrated red corpuscles in the container causes the separation front to approach the passage between the discs of the stationary housing. At this point, the process must be interrupted to prevent the outflow of red corpuscles from the cell. The supply of whole blood is then interrupted and the mandrel rotating the cell is stopped. The cell is free of the lighter fractions and is full of concentrated red corpuscles which can be sucked through the central conduit to empty the cell and to be sent on to the intended use.
A distinct disadvantage of these known cells is that the extraction of the concentrated red corpuscles is possible only when these red corpuscles have completely filled the cell; and therefore only after a substantial amount of blood has been centrifuged. This disadvantage is particularly relevant in case of intraoperative autotransfusion, that is, recovery of blood spilled by a patient during surgery. This blood is sucked and combined with a physiological solution for washing, and sent to a cell for separation of the red corpuscles. It is vitally important to rapidly reinfuse the red corpuscles to the patient. With known cells, this rapid reinfusion is clearly impossible, since it is necessary for the cell to be completely filled with red corpuscles in order to stop blood separation and extract these red corpuscles. Use of small-volume cells does not solve the problem, since it is impractical to have a range of dimensions such as to optimized performance in the variety of actual case. The above description and disadvantages apply to the separation of red corpuscles from whole blood and also for separation of red corpuscles from the physiological solution.